The invention relates to a method for rounding bushings wherein a sheet bar is inserted into a clearance between a core and a first shaping die having a first shaping chamber with an inner profile which at least approximately complements the outer profile of the bushing and which extends over at least half of the circumference of the bushing, that the sheet bar is bent approximately in the form of a U through relative movement of the core into the first shaping chamber during a pre-shaping step, that the core penetrated into the first shaping chamber shapes both legs of the U-shaped formed body in a final shaping step to a bushing through relative movement into a second shaping chamber of a second shaping die, and that the edges of both shaping chambers of both shaping dies terminate in parallel end face planes of the shaping dies, with these end face planes at least approximately contacting each other when the two shaping chambers are closed.
A method of this type is known. Most round housings, bushings and bearing sleeves are bent in this fashion from pre-stamped sheet bars; however, the result after the final shaping step is unsatisfactory, mainly because rounding is incomplete in the vicinity of the end face planes of the shaping dies. Irregularities are also observed at the bushing ends. In most cases, it is therefore necessary to finish the bushings thereafter by a sizing process. It is also impossible to avoid polishing marks on the bushing surfaces with the known methods, and high-quality materials, e.g. materials having multiple layers, plastic-coated sheet bars and the like, cannot be processed by this method without all 10 introducing surface damage.